.root_box {
    display: flex;
    /* 主轴默认方向：从左往右 */
    flex-direction: row;
}

.tree_box {
    padding-top: 10px;
    padding-left: 10px;
    border-radius: 5px;
    border: 1px solid #f0f0f0;
    margin-top: 15px;
    margin-left: 10px;
    width: 260px;
    height: calc(100vh - 100px);
    overflow-y: auto;
}

.main_box {
    margin-right: 10px;
    padding-top: 10px;
    border-radius: 5px;
    border: 1px solid #f0f0f0;
    margin-top: 15px;
    flex: 1;
    margin-left: 10px;
    height: calc(100vh - 100px);
}